Production of stencil sheets for use in duplicating



Patented Oct. 27, 1931 ARMAND DE WAELE, OF LONDON, ENGLAND,

PATENT OFFICE ASSIGNOB TO 1). GESTETNER, LIMITED, OF

LONDON, ENGLAND PRODUCTION OF STENCIL SHEETS FOR USE IN DUPLICATING- No Drawing. Application filed November 22, 1928, Serial No. 321,275, and in Great Britain December 6, 1927.

vThis invention'relates to stencil sheets for use in duplicating manuscript or typewritten matter, drawings and the like of thekind in which the ink-resisting medium of the 5 stencil sheet is adapted to be displaced or its character altered by the local application of pressure to the stencil sheet with the aid of a style or by type faces.

The object of the present invention is to provide an improved stencil sheet of the kind in which the ink-resisting medium of the stencil sheet contains as its essential gelatinizing constituent a cellulose derivative such, for instance, as a cellulose ester and particu- 15 larly nitrocellulose together with a tempering agent or agent adapted to modify the physical properties of the gelatinzing constituent in such manner as to facilitate stencilizing.

Accordingto the present invention an hydroxy fatty acid in the free state is included in the composition as a tempering agent. I v Thus, in accordance with the invention, ricinoleic acid in the free state may be employed. In this connection it may be remarked that castor oil, which of course is composed mainly of the triglyceryl ester of ricinoleic acid, has been employed as a tempering or softening agent in the'production of stencil sheets the essential gelatinizing constituent of which is nitrocellulose.

The employment of ricinoeic acid,.however, in the free state possesses certain advantages over the use of triglyceryl ester of the said acid in the production of stencil sheets of this cellulose ester type in that, for instance, its employment enables stencil sheets to be obtained which are of a less adhesive character than similar sheets produced with the aid of castorloil, which consists wholly or mainly of the triglyceryl ester of ricinoleic acid; 'Moreover, as ricinoleic acid and other higher hydroxy fatty acids do notharmfully afiect rubber by causing it to swell and warp as do the saturated non-hydroxy fatty acids, stencil sheets pro- .duced in accordance with the invention do not exert a harmful effect upon the rubber in feed rollers and other rubber parts of typewriters with which they are brought into contact in the operation of stencilizing.

Normally ricinoleic acid will be employed as the sole tempering agent or at least as the main tempering agent.

The proportion of ricinoleic acid relative to the essential gelatinizing constituent of the coating composition will vary in accordance with the character of the said constituent or the physical strength thereof when in the 0 form of a film. WVith nitrocellulose as the essential gelatinizing constituent the proportion will vary in accordance with the variation in the viscosity of the solution formed by dissolving a given amount of the nitrocellulose in a given solvent. Usually the proportion of ricinoleic acid will be greater with nitrocelluloses giving solutions of higher viscosity than with nitro'celluloses giving less viscous solutions. The ratio of nitrocellulose to ricinoleic acid will usually be from 1: 10 to 1: 16.

The following-particulars are given by way of example to illustrate a suitable manner of carrying the invention into effect.

To 6.6 litres ,of a 6% solution of scrapphotographic film dissolved in ether-alcohol one and a half parts by volume of alcohol to one part of ether are added 1200 grams of a titanium white pigment and 4000 grams of ricinoleic acid and to the mixture is added six litres of a mixture of one and a half parts by volume of alcohol to one part of ether, the whole being thoroughly mixed.

' Yoshino paper is coated with this composition in any known manner, as for instance by drawing sheets of yoshino paper over a roller partly immersed in a body of the composition. The coated sheets are dried under normal atmospheric temperature, say F and pref- 'erably under conditions as to humidity corresponding with, a wet bulb thermometer reading of 50 F.

I claim:

1. A stencil sheet coating which includes a cellulose ester and a hydroxy fatty acid of the ricinoleic series in the free state as the tempering agent therefor.

2, A stencil sheet coating which includes a cellulose ester and ricinoleicacid as the tempering agent therefor.

3. stencil sheet coating consisting essentially of nitrocellulose and a hydroxy fatty acid of the ricinoleic series in the free state as the main tempering agent.

4. A type impressionable stencil sheet comprising an open porous base having a coating including a cellulose ester and a hydroxy fatty acid of the ricinoleic series in the free state as the main tempering agent.

. 5. A stencil sheet adapted to be stencilized by pressure comprising an open porous base having a coating including nitrocellulose and a hydroxy fatty acid of the ricinoleic series in the free state as the main tempering agent.

6. A stencil sheet adapted to be stencilized by pressurecomprising an ink-resisting me- I dium consisting essentially of nitrocellulose and ricinoleic acid as the main tempering agent for the nitrocellulose.

' 7. A stencil sheet a'da ted to be stencilized by pressure consisting o yoshino paper coated with a cellulose ester in association with a hydroxy fatty acid of the ricinoleic series in the free state as the main tempering agent.

8. A stencil sheet adapted to be stencilized by pressure consisting of yoshino paper coated with nitrocellulose in association with a hydroxy fatty acid of the ricinoleic series in the free state as the main tempering agent.

9. A stencil sheet adapted to be stencilized by pressure consisting of yoshino paper coated with a cellulose ester in association with ricinoleic acid as the main tempering agent.

10. A stencil sheet adapted for stencilizing by pressure, consisting of a base of fibrous material having a coating including esters of polysaccharides and hydroxy fatty acids of the ricinoleic series.

11. A stencil sheet adapted for stencilizing by pressure, consisting of a base of fibrous material having a coatln including esters of polysaccharides and riclnoleic acid.

11 testimony whereof I have signed my name to this specification.

ARMAND pm WAELE.

sesame 

